Our primary objective is to investigate the nature of speech sounds to find out why they are so effective for human communication and so readily learned by children. The reasons have to do with the status of speech as a complex code that serves to match the requirements of the phonetic message to the properties of the ear and the vocal tract; though the efficient speech code is complex, it is normally processed adequately by mechanisms that may be unique to man. A related objective is to study reading, a secondary skill based on speech but more difficult by far to master. To carry out these objectives we propose to do a number of experiments and, where necessary, to develop further the appropriate methods. Our proposal falls into five broad categories. I. The Speech Code: We will try to learn more about the acoustic cues, with particular attention to natural, fluent speech and to the kinds of context conditioned variations that are found there. II. The Perceptual Processing of Speech: In this section our concern will be with questions about the distinctive characteristics of speech perception and with the possibility of distinguishing among perceptual stages. III. Acquisition of the Speech Code: Endowment and Experience: Here are studies, including especially cross-language comparisons, that provide a basis for assessing the effects of experience on speech perception. IV. Reading as a Coalitional Skill: Taking advantage of knowledge about speech and visual information processing, we will study what the child must do if, in reading, he is to make contact with the linguistic system he already possesses, with emphasis on the assumption that reading is a complex, heterarchical (or coalitional) kind of skill. V. Instruments and Techniques: This section looks forward to the further development of the instrumental methods that have in the past been so important to our research.